Exterior face of floor mat backing



FIG. 1 is a plan view of a first embodiment of the exterior face of floor mat backing of my design; and,

FIG. 2 is a plan view of a second embodiment of the exterior face of floor mat backing of my design with the word “LOGO” shown in broken lines for illustrative purposes only and forming no part of the claimed design.

The broken line showing in the drawing Figures is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for an exterior face of floor mat backing, as shown and described. 